Manufacture of metal-filament lamps.



W. G. ARSEM.

MANUFACTURE OF METAL FILAMENT LAMPS.

APPLIOATIOI rum) n12. 16, 1907.

903,826 Patented Nov. 17,1908.

Witnesses: Inventor;

WiHiamCfIrsem,

- Ah, By W fltty.

UNITED STATES. PATENT OFFICE. WILLIAM G. ARSEM, OF SOHENEGTADY, NEWYORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A'CORPORATION OF NEW YORK.-

. 'MANUFA'CTURE OF METALFILAMENT LAMPS.

Specification of Letters Patent.

Patented Nov. 17, 1908.

Application filed March 16, 1907. Serial No. 362,617.

To all whom it may concern:

Be it known that I, WILLIAM C. ARsnM, a citizen of the United States,residing at Schenectady, county of Schenectady, State of New York, haveinvented certain new and useful Improvements in Manufacture ofMetal-Filament Lamps, of which the following is a specification.

Lamp filaments of such refractory material as :tungsten molybdenum,boron, and similar elements can be advantageously connected toleading-in conductors orsupport wires by a fused or welded joint. Such ajoint furnishes a secure connection to the filamerit and is entirelyfree from any carbonaceous or vaporizable material which mightdisintegrate under the heating action of the incandescent filaments andmight act injuriously-on the metal thereof.

According to my present invention, a fused or welded joint may be madein a convenient and economical manner Without the use of costly orelaborate apparatus.

The implements whereby the joint is produced possess certain novelfeatures, and are hereinafter described in detail.

During the fusing or welding operation electrical energy is applied tothe junction of the filament with its leading-in or support Wire, andthis energy is suflicient to melt down a portion of the wire and producea globule of metal surrounding and in inti mate contact with thefilament. When the globule cools, a tight joint of high electricalconductivity is produced. Such metals as tungsten are readily oxidizedand must be protected from the deteriorating action of the are when theweld is made. I find that this difficulty may be overcome by projectinga jet of reducing gas, such as hydrogen, directly on the joint so thatthe jet incloses all those parts of the filament which come in contactwith the arc or with the highly heated metal fused by the arc. Thecooling action of the jet insures arapid solidifying of the fused metalafter the arc is interrupted.

t also assists in controlling the length and location of the arc. I findthat the reducing gas, such as hydrogen, will not take fire provided itis surrounded by a jet of carbon dioxid or its equivalent. These gaseousjets may be small and may be in operation only while the joint is undertreatment. The consumption of gas is small and its use does not 1 in anyway interfere with the manipulation of the welding instruments orelectrodes.

The accompanying drawing illustrates all the apparatus necessary inapplying my improved method, though for some complex lamp structures, aswhen a plurality of fila ments are mounted on a single stem, thearrangement might be somewhat modified to secure greater ease in thesuccessive fusion of joints. Such modifications are obvious and requireno illustration.

Figure 1 is a perspective view illustrating the welding operation; Fig.2 is a perspective of a combined welding electrode and gas distributor;Fig. 3 shows the position of the filament before the welding operation,and Fig. 4 shows the finished weld.

In Fig. 1 a lamp stem 1 is detachably held in a springpressed clip 2adjustably mounted on a slotted standard 3. The standard is secured to abase block 4 of wood or other suitable material. A block of insulation5, such as hard rubber. is placed on the base block and serves as asupport for a metal filament 6, during the operation of welding thatfilament to the leading-in wires 7 of the lamp stem. These leading-inWires may be of platinum each bent into a hook forming a seat for thetungsten filament as illustrated in Fig. The vertical adjustment of thelamp stem 1 permits accurate adjustment of the filaments on the hooks ofthe Wires. A gas projector 8 is arranged below the junction of filamentand wire and serves to supply concentric jets of gas to the joint duringthe welding or fusing operation. This jet deflector consists of acentral nozzle tube 9 communicating through a glass tube 10 and a rubbertube 11 with a suitable source of hydrogen or other reducing gas. Aroundthis central. nozzle 9 'is a larger nozzle 12, disposed to form anannular discharge opening through which an inert gas such as carbondioXid may be projected to envelop the jet of hydrogen. The carbondioXid may be supplied through tube 13. Fig. 2 shows the gas projectoras provided with a central platinum wire 14, but this wire is notnecessary when the welding operation is carried out as illustrated inFig. 1. A suitable valve mechanism 15 may be provided for simultaneouslycontrolling the flow of gas through the rubber tubes 11 and 13. Asillustrated, this valve mechanism consists of a brass standard 16mounted on the base block and carrying a pivotally supported lever 17',the end of which 1s held down tightly on the rubber tubes by a codedspring 18. When the welding operation is performed, this valve is openedto permlt the passage of gas from thenozzles 9 and 12. Two electrodes 19and 20 are used for drawin the are which produces the weld. These eectrodes may be of platinum or carbon and supplied with energy from abattery or other suitable source.

To form the weld, the electrode 19 is placed in contact with theleading-in wire 7 and electrode 20 is touched to the end of the hook inwhich the filament is seated. The electrode is then withdrawn to producea welding are which fuses up the hook and produces a globule of meltedmetal completely inclosing and in intimate contact with the metal of thefil'ament. The hydrogen jet projected by nozzle 9 quickly cools theglobule of fused metal, it also prevents the are from drawing out to anundue length, and prevents oxidation or other deterioration of thefilament or of the leadingin wire during the sealing operation. Theouter jet' of carbon dioxid projected from nozzle 12 prevents ignitionof the hydrogen.

After the weld is completed at one joint the gas projector is movedoutward in the slot 21 and placed immediately beneath the second joint.

It is sometimes convenient, as when the lamp structure is'complicated,to combine one of'the welding electrodes with the gas projector so thatthe projector and electrode may be manipulated simultaneously with onehand. Fig. 2 illustrates the electrode thus arranged. This arrangementhas the further advantage that the welding arc is of necessity produceddirectly in the center of the hydrogen jet and at the proper distancefrom the nozzle. This feature is of importance when the weldingoperation is to be carried out commercially on a large scale and by chealabor. If the lamp structure is compllcated, as for instance when thelamp includes a plurality of loops, this combined electrode and gasdeflector is of great convenience in welding the several joints of thestructure. The lamp filaments and other parts may be assembled in theopen air and may remain stationary while the welding electrode and itsincloslng jets are moved from one joint to another.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,

1. The method of joining a filament to ,a conductor which consists inelectrically heating the joint and simultaneously rejecting thereon ajet of reducing gas inc osed in a jet of inert gas.

2. The method of joining a refractory metal filament to a conductor,which consists in electrically fusin a portion of said conductor aboutsaid filament and simultaneously projecting on the fused parts a jet ofreducing gas lnclosed in a jet of inert as. g 3. The method ofprotecting a metal filament from deterioration in the presence of anelectric arc,-which consists in locally applying a jet of reducing gasenveloped in a jet of inert gas.

4. The method which consists in arranging a metal lamp filament inproximity to a metal wire, directing a jet of inert gas on a portion ofsaid filament, projecting a jet of reducing gas .under cover of saidinert gas, and drawlng an arc in the center of said reducing gas to meltdown a portion of said metal wire and join the wire to the filament.

5. An implement for fusing metal lamp filaments to conductors,consisting of concentrically arran ed nozzles, and an electrodeprojecting om one of said nozzles.

6. An implement for fusing metal lamp filaments to conductors,comprising an electrode, means for projecting a jet of gas to inclosethe end of said electrode, and means for projecting a jet of inert gasto inclose saidjet of reducing gas.

In witness whereof, I have hereunto set my hand this 14th day of March,1907.

WILLIAM G. ARSEM.

Witnesses HELEN ORFORD, MARGARET E. 'WOOLLEY-

